Photometric device



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Sept. 8,. 1925. V. C. CRTES PHOTOMETHIG DEVICE Filed Jan. V9, i920Patented Sept. 8, 1925..

U-Nrr s PATENT OFFICE.

villen. c. Cairns, or cercas-o, immers, 'Assrcnon To rnorolrn'rnrcrnonccms comentarios, en cercano, immers, A comonnrron. or DELAWARE'rnoromnrnic DEVICE Application r11-ed January 9, 1920. Serial No.350,413?.

To all lwhawnt may concer/n:

Be it known that I, Vmcn. C. Cairns, a 'citizen of the United States,residing at Chi.- cago, in the county of Cook and State of Illinois,have invented a' certain new and useful Improvement in Photonietric De#vices, of which the following is, a full, clear, concise, and exactdescription, reference being had to the accompanying drawings,

'forming a partof this specilication.

My invention relates to photometric de! tion of variations in suchdevices. In' my Patent No. 1,379,172, patented May 24, 1921-, I setforth a system including an electron discharge tube and a pair ofphotoelectric cells so arranged 'that the cin-rent variations or" one oisaid photo-electric cell is amplified by the electron discha-rv'e tube.My present invention concerns itself with the rovision of means tosecure e second amp ification.

My invention concerns itself with the amplification of the variationsor" an electron discharge tube by a second electron' disn charge tube 1nsuch manner that the second electron discharge tube need not be broughtinto resonance with the first.

I will explain one form which my invention may take more in detail byreierringto the accompanying drawing illustrating diagrammatically a.system arranged 1n accordance with my invention.

Referring more particularly to the drawing, I show an electron dischargetube l0 having the ilamentl, grid 12 and plate 13.

A suitablebattery 1li serves enel-gine" 'the filament 11 thereby to1place the tube 10 in condition for establishing an electronic streamsuch encrgizatic-n being sulicient to bring about a satura-ted conditionin said tube. A photo-elcctriccell i5 has one oi its terminalsvconnected to the grid 12 and its remaining terminal. connected 'with abattery 16, whose fr terminal is vconnected with a conductor 17fern-iin,4 part oi the external circuit oi the tube 1?. This conductor17, as readily apparent from the ib lustration, -is connected 'to oneterminal of the filament 11 and therefore to one terminal .of thebattery le. It will be noted that the conductor 17 is associated' withthe negative termina?. of the battery 1ct, the poeitve terminal of thebattery f16, the nega.- tive terminal of the battery' 18. and thenegative terminal of the battery 19.

, Although definite voltages are -not absoL lutely required, I havefound in practice that in the particular arrangement of. apparatus witha given particular Usize of photoelectric cell and electron dischartube, that I get goed results if the voltage oi the battery 14 is aboutsix volts, the voltage of and twenty volts and the voltage of the battery 19 about three hundred and ty volts.

The external circuit of the electron disthe batteries 16 and 18 each onehundredvv vices,l together with means for the amplificaciiiege tube 10extends by Way of the conl 'ductor 17 through the battery' 19,lconcluetor v2O, to a second electron discharge tube 21, conductor tubel0.

I provide a second .photo-electric celll which, as seen .from thedrawing, I connect to the electron discharge tube 10 in einem nerreverse to theconnection of the .photoelectric cell 15. Thephoto-electric cell 23 has certain apparatus which will be pres? cntlyexplained whereby objects, such as the obgect 24, and which objects areof ydifterent color or light effect, affect the photo-y 22, back to thevplate 13 of the;

electric cell 23 in proportion to their lightf ing edect so that theelectricalvariations in..y said photo-electric cell 23 are 1n accordancewith the color or other lighting eect of successive objects 24 that areplaced Within the range of the photo-electric cell 23.

Cell 15 is unsensitized so that its characteristics remain constantunder the inlinence of the steady light source 25, While cell 23 issensitized so as 4to malte it more sensitive and more readily responsivetei-slightv changes .in light. It is therefore more deliy cate. f In oneormbi' application of my im.'y proved device, I have utilized it rfordetermining the color of cigars placed Within the I range of the cell23, such a cigar being die` grammaticallyindicated as the object 2li/inthe drawing.

AA screen 24a placed between the oli/act 24 and the cell 23 is of suc-hcharacteristics that it prevents the 60 cycle Hertzien waves'. Y'

(due to the use of 6,0 cycle the .lamps 27 and 28) Atrom I Vfind 'thatthe variations in the external circuit lof the tube 21 relative to thevvariations in the tube l0 follow substantially astraigh't lineequation.. This provides'a very sim le and etectivemethod of giving" usa straight line amplification anda so rovides va very simple andeffective meth of obtaining a multiple amplification without the'.necessity of lbringing the various tubes into resonance. l

From whatv has been thus described the v nature of my invention Willbereadily apparent, and it will also be apparent that my invention is notlimited to the specific arrangement as herein disclosed.

I claim the followingz- 1. A system of the 'character described,

comprising an electron discharge tube having a plate and a grid, ahoto-electric cell tcharge tube, to thereby amplify the electricalvariations of said first aforesaid tube having a plate and ag grid, theplates of said tubes being connected-together and the grids of lsaidtubes being onnectedtogether. 1

2. A system of the character described,

' comprising an electron discharge tube having'a-plate and a grid, ahoto-electric cell connected to said tube W ereby the variations ofcurrent in said cell are amplified by said tube, a furtherphoto-electric cell to control `the residual lelectric condition of saidtuberand a second similar electron discharge tube directly connectedinto the circuit of said first aforesaid electrondischarge tube tothereby amplify the electrical variations of said first aforesaid tubehavin a plate and a grid, the plates of said tu s being connectedltogether and the grids of said tubes being connected together.

A system of the character described, comprising an electron dischargetube having a plate and a grid, a photo-electric cell connected to thegrid of said tube, whereby the variations of'current in said cell areamplified by said tube, and a second similar electron discharge tubedirectly connected into the 'circuit of said iirst aforesaid electrondischarge tube to thereby amplify the electrical variations of saidfirst aforesaid tube having aplate and a grid, the plates of said tubesbeing connected together and the grids of said tubes being, connected together, the. plates of said tubes being unconnected with the grids ofsaidtubes.,

4. A system of the character described,v I

comprising lan'electron discharge tube hav ing a plate'and a grid,'meansfor energizing said tube, means for causing variations of the electricalconditionsfin said tube, anda second similar electron discharge tubedirectly connected to the said'irst aforesaid.

electron discharge tube to amplify the electrical variations in saidfirst aforesaid electren discharge tube having a plate and a grid, theplates of said tubes bein connected together and the grids of sai tubesbeingfconnected together, the-plates of said ltubes being unconnectedwith the grids of said tubes.

In wltness whereof, I hereunto subscribe my name this vIReIL c. Cairns.

20th day of December,

